Completion of wells



Sept- 24, 1946, o. D. .HARPER COMPLETION OF WELLS f 'Filed oct. 19, 1942 2 Sheets-Shea?l 1 6.. .o Av O A7' TOHNEY Sept. 24, 1946. o. D. HARPER COMPLETIONA OF WELLS Filed Oct. 19, 1942 2 sheets-sheet 2 5 TAH ex/76W INVENTOR,

ATTORNEY- Patented Sept. 24, 1946 COMPLETION OF WELLS Orvie D. Harper, Vandalia, Ill., assignor to Standard Oil Development Company, a corporation of Delaware Application October 19, 1942, Serial No. 462,552

Claims. 1

The present invention is directed to a method for completing wells drilled for the production of petroleum from two or more producing horizons spaced from each other.

In the past, methods have been developed for the production of petroleum from a plurality of spaced producing horizons by using in the casing sections of drillable metal known as windows. It is the principal object of the present invention to provide a method for accomplishing this same result without resorting to the use of these expensive and scarce drillable metals.

The nature of the present invention will be best understood from the following detailed description of the accompanying drawings, in which Figure l is a perspective of the elements used in one embodiment of the present invention;

Figure 2 is a vertical section of these elements in position for the rst stage of the completion method of the present invention;

Figure 3 is a similar View of lthe elements in position for the second stage of said method; and,

Figure 4 is a similar View, with Ithe elements in position for the next succeeding stage of said method.

Referring to the drawings in detail, numeral I designates the lower section of a string of casing, this section being provided at its lower end with diametrically opposed laterally `extending splines 2. These splines areV adapted to work in J-slots 3 provided in the upper end of a special section 4, the lower end of which is adapted to have screw-threaded engagement with a casing shoe 5, provided with the conventional iioat 6 for cementng purposes. The casing shoe is provided at its lower end' with downwardly extending circumferentially spaced prongs 'I which serve the purpose hereinafter specied.

In Figure 2 is shown a bore hole 8 traversingV two spaced producing sands 9 and Ill. The hole is drilled with the final desired diameter to the top of producing section lil, and into this formation is drilled a rat hole II of reduced diameter. The assembly shown in Figure 1 is attached to the end of a string of casing I2 with a conventional oat collar I3 having float I4 arranged between the end of the string of casing and the aforedescribed assembly. The length of section 4 is determined by the distance between the producing sands and the length of section I is optional.

With the parts in the relation shown in Figure 2, the assembly is lowered until the prongs 1, strike the shoulders of the rat hole. The assembly is then raised slightly so as to insure that the bottom of .the casing shoe is not resting on the rim of the rat hole, and cement is pumped in in the usual manner. After a pre-determined amount of cement sufficient to illl the space between the casing and the bore hole wall ybetween .the two producing horizons has been pumped into place, the entire assembly is seated as shown in Figure 2 with the bottom of the casing shoe resting against the upper rim of the rat hole and the prongs imbedded in the producing formation I5.

The casing shoe and section 4 when in this position are not free to turn `so that by turning the casing to the right the splines 2 are moved over to a position where they may readily be withdrawn from the J-slots. The string of casing with section I is then picked up to a point shown above the upper producing horizon and cementing is resumed until the required amount of cement is in place. After the cement is set, it and the floats are drilled out of the casing and the producing horizons shot with nitroglycerin to free their surfaces and to increase the amount of exposed producing surface. In Figure 4 the parts are shown in the position they assume in the final cementing stage.

It will be apparent that the procedure heretofore described can be varied without departing from the scope of the present invention. One variation may involve the location of the casing float collar in section 4 below section l, rather than above it. When lthis is done the assembly is lowered into the position shown in Figure 2 and the cement is followed by a plug which is pumped down to the float collar. Section I is then disengaged from section 4 and the cement above the iioat collar and above section 4V is pumped out. 'I'hen with the parts in the position shown in Fig. 4 the hole above the producing horizon 9 is cemented. By this procedure the amount of cement to be drilled out of .the casing is reduced and the faces of the producing formation are kept free of cement.

It can readily be seen that the aforedescribed arrangement lend-s itself readily to separate production from the several horizons. With the parts in the position shown in Fig. 4, for example, after the cement and the floats have been drilled out of the casing, a tubing can be lowered from the surface into section 4 and packed off in this section with the result that oil from formation I0 is produced through the tubing and oil from formation 9 produced through the casing without any mixing of the two. In fact, with this latter arrangement, where there is only one 3 producing horizon such as that indicated by numeral I0, the upper part of the casing above 'section 4 can be omitted entirely thereby cheapening greatly the cost of completing the well` While the Ainvention has been described with reference to production from two horizons, its adaptation to production from more than two horizons is a simple matter. For a third horizon, for example'it is necessary only to have another pair of sections corresponding to l and 4 with the bayonet slot connection arranged to be released by rotation in a direction opposite from that required to release the lowermost connection. The number of sections which can be utilized can be increased by utilizing J-slots re quiring different degrees of rotation, as well as rotation in different directions, for disengagement of the splines from the slots. y

While the prongs 'l constitute a very desirable adjunct to the completion assembly described, their usel may be dispensed with. In this case care must be taken that in the first cementing stage only suicient cement is employed to secure the lower section in place when it is seated on the rat hole, as shown in Fig. 3, without covering up the J-slots because it is necessary to permit the cement to pass at least the first setting stage before section l can be rotated with respect to sec-f tion 4. Y

The nature and objects of the present invention having been thus described and illustrated, what is claimed as new and useful and is desired to be-secured by Letters Patent is:

1. A method for completingA a, well having a plurality of producing horizons which comprises lowering into the well a casing having separable sections corresponding in number to the producinghorizons into a position where the lowermost section is just above the ,lowermost producing horizon, cementing the lowermost section of the casing in place, disengaging the remainder of the casing from the lowermost section and raising it until its lower end isadjacent the upper end of the next higher producing horizon, cementing the new lowermost section in place, repeating these operations to the extent required by the number of producing sections and drilling out residual cement from the several sections.

2. A method for completing a well traversing a plurality of producing formations so as to permit production from at least two formations which comprises lowering into the well a casing having at least two sections separable by rotation relative to each other to a point where the lowermost section terminates adjacent the top of the lowermost producing formation, forcing cement into the space between the lowermostsection and the wall of the bore hole, securing the lowermost section against rotation, rotating the upper section with respect to the lowermost section to separate them, withdrawing the upper section until its lower end is adjacent the top of the next higher producing formation, cementing the upper section in place and drilling out cement from the interior `of said sections.

3. A method for completinga well having two' producing formations at different levels which comprises drilling a bore hole of the nal desired diameter to the top of the lower producing formation, drilling a rat hole into said formation, lowering into the bore hole a casing Vhaving at least two sections separable by rotation relative to each other to a'point where the lowermost section terminates adjacent the top of the lowermost producing formation but spaced from the top of said rat hole, forcing cement into the space between the lowermostV sectionV and the wall of the bore hole, seating said lowermost section on the top ofv said rat hole and securing it against rotation, rotating the upper section of the casing with respect to the lowermost section to separate them, withdrawing the upper section until its lower end is adjacent the top of the higher producing formation, cementing the up-V persection in place and drilling out cement from the interior of said sections. 4. The method of cementing casing in a Well having upper and lower producing strata which comprises discharging cement through the casing and from adjacent the bottom thereof to cement the bottom of the casing in place between the strata, separating the casing and lifting that portion of the casing above the point of separation to expose the upper stratum, and discharging cement through the lifted portion of the casing adjacent the bottom thereof to cement the lifted portion in place above the upper stratum. 5. 1A method for completing, a well traversing a plurality of producing formations so as to permit production from at least two formations which comprises lowering into the Well a. casing having at least two sections separable by rota` tion relative to each other to a point where lthe lowermost section terminates adjacent the top of the lowermost producingV formation, forcing cement into the space between the lowermost section and the wall of' the,` borehole, securing" the lowermost section against' rotationL rotating; the upper Vsectionwith respect to the lowermost sec-V tion to separate them, withdrawing the' upper section until its lower end is adjacent thetop of the next higherA producing formation, cementingthe-upper section in place. Y1.v j

' VORVIE D.HARPER.' 

